Images displayed on display devices may be generally divided into two types: synthetic images and natural images. The synthetic images are images that are artificially synthetized by using a computer, such as cartoons, application icons, etc. And the natural images are images that exist in the natural world and are captured by an image acquiring device, for example, a camera. In general, a synthetic image is artificially plotted according to characteristics of a display device such that contents of the synthetic image conform to the characteristics of the display device. For example, a beautiful image may be plotted according to a bit depth, a color gamut and a contrast ratio which the display device is capable of presenting. A natural image generally exhibits contents really existing in the natural world, without being processed with respect to characteristics of a specific display device. Thereby, a natural image may be post-processed using a specific image processing technique to make the natural image more beautiful. Post-processing of a synthetic image, however, may damage the beauty of the synthetic image.
Therefore, before performing a post-processing on an image, it is necessary to identify the type of the image, such that an operation (e.g., post-processing) may be determined whether to be executed on the image according to the identified type of the image. In this way, the beauty of the image may be retained.
Conventionally, the type of an image may be identified by calculating an entropy of the image. If the entropy of the image is greater than a preset threshold value, the image is determined as a natural image; and if the entropy of the image is smaller than or equal to the preset threshold value, the image is determined as a synthetic image.